public ActionResult Index(string sortOrder, string currentFilter, string searchString, int?page)
{
#region Sorting
// This will keep the current sort order the same while paging
ViewBag.CurrentSort = sortOrder;
/*
* Sorting implementation receives a sortOrder parameter from query string in URL,
* does descending on Date by default
*/
ViewBag.DateSortParm = string.IsNullOrEmpty(sortOrder) ? "Date" : string.Empty;
ViewBag.TitleSortParm = sortOrder == "Title" ? "title_desc" : "Title";
#endregion
#region Paging
/*
* The first time the page is displayed or if no page /sorting has been clicked, all will be null. If
* a page link is clicked, a page variable will contain the current page number to display. This also resets paging
* 1 if the searchString changes
*/
if (searchString != null)
{
page = 1;
}
else
{
searchString = currentFilter;
}
// Provides the view with the current filter string inbetween changing pages and gets restored to filter box when page gets re-displayed
ViewBag.CurrentFilter = searchString;
#endregion
//// Uses LINQ to Entities and creates an IQueryable variable called blogposts
//// Could have dynamically created a LINQ statement instead o writing different ones for each sort order
IEnumerable <Blogpost> blogposts = _blogpostRepository.GetBlogposts();
#region Filtering
// Adding in a conditional where clause if the searchString is not empty
/*
* Using if statement incase you change repositories, so if you call an IEnumerable (which is a .NET
* Framework implementation) you won't get all rows if the search string is empty and if you call an
* IQueryable object (which is a database provider implementation) you still will not get any rows when the search
* string is empty. The ToUpper also does the same since the .NET implementation of the Contains method is case-sensitive
* while the EF SQL Server providers perform case-insensitive comparisons
*/
/* Since changing from using the context to the repository, the 'var blogpost' above goes from an
* IQueryable to an IEnumerable which returns all blogposts and then filters through them. This can
* be inefficient with large amounts of data
*/
if (!string.IsNullOrEmpty(searchString))
{
blogposts = blogposts.Where(b => b.Title.ToUpperInvariant().Contains(searchString.ToUpperInvariant()) ||
b.Subtitle.ToUpperInvariant().Contains(searchString.ToUpperInvariant()) ||
b.User.UserName.ToUpperInvariant().Contains(searchString.ToUpperInvariant()));
}
#endregion
#region Sort Order Switch
switch (sortOrder)
{
case "Date":
blogposts = blogposts.OrderBy(b => b.CreatedOn);
break;
case "Title":
blogposts = blogposts.OrderBy(b => b.Title);
break;
case "title_desc":
blogposts = blogposts.OrderByDescending(b => b.Title);
break;
default:
blogposts = blogposts.OrderByDescending(b => b.CreatedOn);
break;
}
#endregion
/*
* The ToPagedList extension method acts on the blogposts IQueryable object to convert the query to a single page
* of blogposts in a collection type that supports paging. That single page gets passed to the view. The two ?? represent
*
*/
const int pageSize = 3;
int pageNumber = (page ?? 1);
// No database calls are made until converting the IEnumerable object (blogposts) into a collection using ToList()
return(View("~/Views/Blogpost/Index.cshtml", blogposts.ToPagedList(pageNumber, pageSize)));
}
